Omg, ur having the same problem i am. I took my nail polish off, and i noticed my nails were yellow. I was like omfg. Anyway, yellow nails come from not letting your nail beds air out from nail polish. If ur like me, u kept reapplying and covering over the old polish. I don't know of any remedies, I'm just letting mine air out for a while.
How to fix your yellow nail problem : Lemon juice: Soaking your nails in lemon juice will get rid of those yellow stains. ... Peroxide and baking soda: Mix 1 tablespoon of hydrogen peroxide with 2-1/2 tablespoons of baking soda in a small bowl.
Take a nail buffer, and very gently buff a very thin layer of your nail. The pigments of nailpolish get trapped in your nail surfacr and cause discoloration. To prevent this, either opt for a base coat or resort to light colored nailpolishs such an white and pale colors.